The present invention relates generally to a contingency hydraulic power unit and more particularly to a contingency hydraulic power unit for use in an aircraft/spacecraft.
Hydraulic systems are commonly utilized to provide power required for operating components within aircraft, spacecraft, and the shuttle orbiter. Hydraulic systems have been utilized to power a variety of components including, but not limited to, wing flaps, control surfaces, thrust reversers, steering systems, braking systems, and landing gear. Many of such systems are crucial to the proper operation of the craft. Safety considerations, therefore, often dictate that redundant or contingent hydraulic systems be present to insure proper operation. These redundant hydraulic systems are designed to provide adequate power should the primary hydraulic unit become damaged or malfunction. It is known that these redundant/contingent systems often take the form of duplicate hydraulic units. In some circumstances, such as those involving control surfaces, there may be as many as three or more separate hydraulic systems to provide a greater margin of safety. Although such duplicate systems provide the necessary redundancy, they can often result in negative design considerations involving space and weight requirements. The space required to house these redundant systems as well as the weight associated with their presence can prove undesirable in spacecraft design.
Present shuttle orbiter designs are often sensitive to these space/weight design considerations. The orbiter hydraulic systems have often utilized hydrazine auxiliary power units (APUs) to provide both primary and redundant hydraulic power. It is known, however, that hydrazine is both toxic and flammable and may therefore require its own design safety considerations when used within the orbiter design. Orbiter designs have therefore also utilized electric APUs (EAPUs) to improve such safety considerations. Although the use of EAPUs eliminates some of the safety considerations associated with hydrazine units, present orbiter systems often require three or more electro-hydraulic drive units (EHDU). These drive units must commonly be sized to achieve a single APU landing capability. This results in large, heavy and complex EAPU""s. The use of these new EAPU units, however, can pose a threat to the size/weight characteristics of a successful orbiter design that can be compounded when multiple units are utilized.
Although each EHDU often requires only two modules for normal operation, it is known that a third module may be required to provide high flow capability. High flow capability may be required in a variety of circumstances such as during main wheel touchdown during aircraft landing. During main wheel touchdown, it is common for the hydraulic system to require a peak load demand and an increased flow capability. Although the requirement for high flow may only occur for ten to twenty seconds after weight on wheels, the ability of the EHDU to provide adequate flow during these periods can be critical to the proper operation of the aircraft. Thus a contingency hydraulic unit capable of insuring adequate high flow capabilities during critical times, while reducing the negative weight characteristics associated with redundant modules would be highly desirable.
It is, therefore, an object of the present invention to provide a contingency hydraulic power unit. It is a further object of the present invention to provide a hydraulic power assembly for use in an aircraft with contingent power capabilities.
In accordance with those and other objects of the present invention, a hydraulic power assembly is provided. The hydraulic power assembly includes at least one primary hydraulic power unit providing hydraulic fluid through hydraulic lines to a hydraulic system. The hydraulic power assembly further includes a contingent hydraulic power unit. The contingent hydraulic power unit includes a hydraulic fluid reserve. A gas turbine, powered by a helium storage unit, is capable of supplying the hydraulic fluid reserve to the at least one primary hydraulic unit during high flow requirements.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.